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Changing taps gravity fed system
number-1 - 27/1/24 at 06:02 PM

Evening All

My partner wants new taps on the bath. She has a gravity fed system with hot water cylinder. There are isolation valves for the cold water down supply from the loft but nothing for the hot water even in the airing cupboard

Is there a quick and easy way to isolate the hot water feed without draining the hot water cylinder?

I seem to remember my father sticking a carrot into the cold water storage cistern in the loft but cant remember if it was to change a tap

Cheers

N1


coyoteboy - 27/1/24 at 07:45 PM

Buy a can of freeze spray and work fast. Or just plug the input to the cylinder, power off the immersion heater and drain the lot


JoelP - 27/1/24 at 09:39 PM

You can buy plugs to go in the tank, to block the feed to the cylinder. I'd be tempted to just turn off the water heating and drain it once it's cold.

You often find a gate valve between header and tank, and they're notorious for jamming up.


cliftyhanger - 28/1/24 at 09:39 AM

Just pondering. If you plug the outlet from theecold water tank, and the vent pipe from the hot water tank, let it cool a bit it may be enough to cut the pipe and wack a push fit isolator in. Easy enough to test by opening the hot water tap. If nothing comes out you should be OK.
I wouldn't let the cylinder cool too much, it could collapse under the vacuum.


SteveWalker - 28/1/24 at 10:55 AM

There should be no need to plug the vent pipe. Plugging the feed from the cold-water tank and running off a little bit of hot water from the tap, should empty the small volume of water from the vent pipe and then there is no longer any water above the top of the hot-water cylinder, where the hot water comes out, and flow should stop. The vent pipe remaining open means that there can be no vacuum.

In our house (and at my parents' house), we have a valve to close off the feed to the hot-water cylinder and have made many changes to the hot-water plumbing, using just that. Indeed, a few months ago, at my parents, we actually had the fitting out of the top of the cylinder to fit a Surrey flange, to isolate the shower flow from the tap flow and stop that temperature fluctuation when someone runs a tap.


coyoteboy - 28/1/24 at 10:59 AM

quote:
Originally posted by SteveWalker
There should be no need to plug the vent pipe. Plugging the feed from the cold-water tank and running off a little bit of hot water from the tap, should empty the small volume of water from the vent pipe and then there is no longer any water above the top of the hot-water cylinder, where the hot water comes out, and flow should stop. The vent pipe remaining open means that there can be no vacuum.

In our house (and at my parents' house), we have a valve to close off the feed to the hot-water cylinder and have made many changes to the hot-water plumbing, using just that. Indeed, a few months ago, at my parents, we actually had the fitting out of the top of the cylinder to fit a Surrey flange, to isolate the shower flow from the tap flow and stop that temperature fluctuation when someone runs a tap.


Eh, unless im mistaking the way your plumbing is run, that doesnt physics. If the system is vented you'll empty the cylinder if you do that, assuming the cyl might be upstairs. The weight of water above the tank has almost no impact.


JoelP - 28/1/24 at 04:45 PM

Hot water comes from the top of the cylinder, so it doesn't empty. Easiest solution is just turn off incoming one morning, shower until the header tank is empty, then you have all day to fix the taps. And if you mess it up, at least you're clean lol

[Edited on 28/1/24 by JoelP]


coyoteboy - 28/1/24 at 04:51 PM

quote:
Originally posted by JoelP
Hot water comes from the top of the cylinder, so it doesn't empty. Easiest solution is just turn off incoming one morning, shower until the header tank is empty, then you have all day to fix the taps. And if you mess it up, at least you're clean lol

[Edited on 28/1/24 by JoelP]


Ah fair point!


jacko - 28/1/24 at 05:52 PM

If there is no tap to stop water going to the header tank you can go in the loft and tie the ball float up and drain the hot water
But you will need to turn the main tap off to do the cold water tap
Jacko